This invention relates to an improved osteochondral implant fixation method and, more particularly, to such a method in which a recipient opening is prepared for receiving a graft.
In the human body, the knee consists of three articulating components—a femur, a tibia, and a patella—that are held in place by various ligaments. The corresponding chondral areas of the femur and the tibia form a hinge joint, and the patella protects the joint. Portions of the latter areas, as well as the underside of the patella, are covered with an articular cartilage, which allow the femur and the tibia to smoothly glide against each other without causing damage.
The articular cartilage often tears, usually due to traumatic injury (often seen in athletics) and degenerative processes (seen in older patients). This tearing does not heal well due to the lack of nerves, blood vessels and lymphatic systems; and the resultant knee pain, swelling and limited motion of the bone(s) must be addressed.
Damaged adult cartilages have historically been treated by a variety of surgical interventions including lavage, arthroscopic debridement, and repair stimulation, all of which provide less than optimum results.
Another known treatment involves removal and replacement of the damaged cartilage with a prosthetic device. However, the known artificial prostheses have largely been unsuccessful since they are deficient in the elastic, and therefore in the shock-absorbing, properties characteristic of the cartilage. Moreover, the known artificial devices have not proven able to withstand the forces inherent to routine knee joint function.
In an attempt to overcome the problems associated with the above techniques, osteochondral transplantation, also known as “mosaicplasty” or “OATS” has been used to repair articular cartilages. This procedure involves removing injured tissue from the articular defect and drilling cylindrical openings in the base of the defect and underlying bone. Cylindrical plugs, consisting of healthy cartilage overlying bone, are obtained from another area of the patient, typically from a lower weight-bearing region of the joint under repair, or from a donor patient, and are implanted in the openings. However, in these cases, if the opening is too large, the graft can rotate in the opening and become loose, which will prevent integration with the surrounding tissues. If the opening is too small, significant cellular damage can occur to the graft during the implantation.
Co-pending U.S. patent application Ser. No. 11/120,136, filed Apr. 30, 2005, addresses the above problems with cylindrical grafts by disclosing a implanting technique involving grafts including at least one bone portion having a cross-sectional profile other than that of a circle and including a mechanical stop to resist rotation. The disclosure of this application is hereby incorporated by reference.
An embodiment of the present invention involves a technique for providing an opening in the defect having dimensions corresponding to those of the grafts disclosed in the above application.